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<topic id="topic1" xml:lang="en"><title id="gt143896">pg_largeobject</title><body>
        <note>Greenplum Database does not support the PostgreSQL <xref
                href="https://www.postgresql.org/docs/9.4/largeobjects.html" format="html"
                scope="external">large object facility</xref> for streaming user data that is stored
            in large-object structures.</note><p>The <codeph>pg_largeobject</codeph> system catalog table holds the data
making up 'large objects'. A large object is identified by an OID
assigned when it is created. Each large object is broken into segments
or 'pages' small enough to be conveniently stored as rows in <codeph>pg_largeobject</codeph>.
The amount of data per page is defined to be <codeph>LOBLKSIZE</codeph>
(which is currently <codeph>BLCKSZ</codeph>/4, or typically 8K). </p><p>Each row of <codeph>pg_largeobject</codeph> holds data for one page
of a large object, beginning at byte offset (<i>pageno</i><codeph> *
LOBLKSIZE</codeph>) within the object. The implementation allows sparse
storage: pages may be missing, and may be shorter than <codeph>LOBLKSIZE</codeph>
bytes even if they are not the last page of the object. Missing regions
within a large object read as zeroes.</p><table id="gt143898"><title>pg_catalog.pg_largeobject</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="131pt"/><colspec colnum="2" colname="col2" colwidth="86pt"/><colspec colnum="3" colname="col3" colwidth="85pt"/><colspec colnum="4" colname="col4" colwidth="147pt"/><thead><row><entry colname="col1">column</entry><entry colname="col2">type</entry><entry colname="col3">references</entry><entry colname="col4">description</entry></row></thead><tbody><row><entry colname="col1"><codeph>loid</codeph></entry><entry colname="col2">oid</entry><entry colname="col3"/><entry colname="col4">Identifier of the large object that includes
this page.</entry></row><row><entry colname="col1"><codeph>pageno</codeph></entry><entry colname="col2"> int4</entry><entry colname="col3"/><entry colname="col4">Page number of this page within its large object
(counting from zero).</entry></row><row><entry colname="col1"><codeph>data</codeph></entry><entry colname="col2">bytea</entry><entry colname="col3"/><entry colname="col4">Actual data stored in the large object. This
will never be more than <codeph>LOBLKSIZE</codeph> bytes and may be less.</entry></row></tbody></tgroup></table></body></topic>